diff --git a/src-web/components/HeaderEditor.tsx b/src-web/components/HeaderEditor.tsx
index 793305ab..87bc08b9 100644
--- a/src-web/components/HeaderEditor.tsx
+++ b/src-web/components/HeaderEditor.tsx
@@ -18,6 +18,7 @@ export function HeaderEditor({ headers, onChange }: Props) {
     <PairEditor
       pairs={headers}
       onChange={onChange}
+      nameValidate={validateHttpHeader}
       nameAutocomplete={nameAutocomplete}
       valueAutocomplete={valueAutocomplete}
       namePlaceholder="Header-Name"
@@ -50,3 +51,11 @@ const nameAutocomplete: PairEditorProps['nameAutocomplete'] = {
   minMatch: MIN_MATCH,
   options: headerNames.map((t, i) => ({ label: t, type: 'constant', boost: 99 - i })),
 };
+
+const validateHttpHeader = (v: string) => {
+  if (v === '') {
+    return true;
+  }
+
+  return v.match(/^[a-zA-Z0-9-_]+$/) !== null;
+};
diff --git a/src-web/components/core/Input.tsx b/src-web/components/core/Input.tsx
index 0a78808d..8c638bbc 100644
--- a/src-web/components/core/Input.tsx
+++ b/src-web/components/core/Input.tsx
@@ -1,11 +1,11 @@
 import classnames from 'classnames';
-import { useMemo, useState } from 'react';
 import type { HTMLAttributes, ReactNode } from 'react';
+import { useMemo, useState } from 'react';
 import type { EditorProps } from './Editor';
 import { Editor } from './Editor';
 import { HStack, VStack } from './Stacks';
 
-type Props = Omit<HTMLAttributes<HTMLInputElement>, 'onChange' | 'onFocus'> &
+export type InputProps = Omit<HTMLAttributes<HTMLInputElement>, 'onChange' | 'onFocus'> &
   Pick<EditorProps, 'contentType' | 'useTemplating' | 'autocomplete'> & {
     name: string;
     label: string;
@@ -41,7 +41,7 @@ export function Input({
   validate,
   require,
   ...props
-}: Props) {
+}: InputProps) {
   const [currentValue, setCurrentValue] = useState(defaultValue ?? '');
   const id = `input-${name}`;
   const inputClassName = classnames(
@@ -80,7 +80,7 @@ export function Input({
           containerClassName,
           'relative w-full rounded-md text-gray-900',
           'border border-gray-200 focus-within:border-focus',
-          !isValid && 'border-invalid',
+          !isValid && '!border-invalid',
           size === 'md' && 'h-md',
           size === 'sm' && 'h-sm',
         )}
diff --git a/src-web/components/core/PairEditor.tsx b/src-web/components/core/PairEditor.tsx
index 5bd532c5..89454757 100644
--- a/src-web/components/core/PairEditor.tsx
+++ b/src-web/components/core/PairEditor.tsx
@@ -10,8 +10,8 @@ import { Checkbox } from './Checkbox';
 import type { GenericCompletionConfig } from './Editor/genericCompletion';
 import { Icon } from './Icon';
 import { IconButton } from './IconButton';
+import type { InputProps } from './Input';
 import { Input } from './Input';
-import { HStack } from './Stacks';
 
 export type PairEditorProps = {
   pairs: Pair[];
@@ -21,6 +21,8 @@ export type PairEditorProps = {
   valuePlaceholder?: string;
   nameAutocomplete?: GenericCompletionConfig;
   valueAutocomplete?: (name: string) => GenericCompletionConfig | undefined;
+  nameValidate?: InputProps['validate'];
+  valueValidate?: InputProps['validate'];
 };
 
 type Pair = {
@@ -40,6 +42,8 @@ export const PairEditor = memo(function PairEditor({
   valueAutocomplete,
   namePlaceholder,
   valuePlaceholder,
+  nameValidate,
+  valueValidate,
   className,
   onChange,
 }: PairEditorProps) {
@@ -140,6 +144,8 @@ export const PairEditor = memo(function PairEditor({
               valueAutocomplete={valueAutocomplete}
               namePlaceholder={namePlaceholder}
               valuePlaceholder={valuePlaceholder}
+              nameValidate={nameValidate}
+              valueValidate={valueValidate}
               onChange={handleChange}
               onFocus={handleFocus}
               onDelete={isLast ? undefined : handleDelete}
@@ -168,7 +174,12 @@ type FormRowProps = {
   isLast?: boolean;
 } & Pick<
   PairEditorProps,
-  'nameAutocomplete' | 'valueAutocomplete' | 'namePlaceholder' | 'valuePlaceholder'
+  | 'nameAutocomplete'
+  | 'valueAutocomplete'
+  | 'namePlaceholder'
+  | 'valuePlaceholder'
+  | 'nameValidate'
+  | 'valueValidate'
 >;
 
 const FormRow = memo(function FormRow({
@@ -183,6 +194,8 @@ const FormRow = memo(function FormRow({
   valueAutocomplete,
   namePlaceholder,
   valuePlaceholder,
+  nameValidate,
+  valueValidate,
 }: FormRowProps) {
   const { id } = pairContainer;
   const ref = useRef<HTMLDivElement>(null);
@@ -272,6 +285,7 @@ const FormRow = memo(function FormRow({
           hideLabel
           size="sm"
           require={!isLast && !!pairContainer.pair.enabled && !!pairContainer.pair.value}
+          validate={nameValidate}
           useTemplating
           containerClassName={classnames(isLast && 'border-dashed')}
           defaultValue={pairContainer.pair.name}
@@ -286,6 +300,7 @@ const FormRow = memo(function FormRow({
           hideLabel
           size="sm"
           containerClassName={classnames(isLast && 'border-dashed')}
+          validate={valueValidate}
           defaultValue={pairContainer.pair.value}
           label="Value"
           name="value"